import org.junit.Test;

import java.util.ArrayList;

public class test {


    @Test
    public void aVoid(){


        ArrayList<String> objects = new ArrayList<>();

        objects.add("0");
        objects.add("1");
        objects.add("2");
        objects.add("3");


        String join = String.join(",", objects);
        System.out.println(join);

        String join1 = String.join(",", "1","2");
        System.out.println(join1);
    }
}
